antrim



Jan. 13, 1959 w. D. ANTRIM 2,868,278

` GAS' BURNER CONTROL MEANS Filed Nov. 29. 1954 2 Sheets-Sheet 1lIJs/VENTOR. )Wa/4M D. #lvm/M lrraeA/er Jam.` 13, 1959 w D ANTRIM2,868,278

GAS BURNER CONTROL MEANS Filed Nov. 29, 1954 2 Sheets-Sheet 2 m f C)INVENToR.

` /5 w/a/AM `D. /wre/M 517.1] SYM/,JEM

GAS BURNER CONTRL MEANS William D. Antrim, Cleveland Heights, Uhio,assigner',

by mesne assignments, to Carrier Corporation, a corporation of DelawareApplication November 29, 1954, Serial No. 473,672

12 Claims. (or. iss-isz) This invention relates to means for controllingoperation of a main gas burner from its fuel source, characteristicapplications of which are in the oven or broiler of a gas cooking range,or in other gas-fired appliances such as a heater or clothes dryer.

The invention pertains to the class of control means including a safetypilot burner in igniting relation to the main burner, a safety valve inthe main gas line arranged for automatic opening and closing dependenton operation of the safety pilot burner, through the medium of athermally responsive device, and a constant pilot burner in ignitingrelation to the safety pilot burner.

Objects of the invention are to provide that the constant pilot may beof minimum capacity, be easily and quickly put into operation, and beprotected against outage during normal cycling of other elements of theinstallation.

Another object is to provide that, upon outage of the constant pilot, asduring a standby period, its own supply of gas as well as that to theconstant pilot and the main burner be automatically cut off, so as toinsure complete `safety for the entire apparatus; yet constant pilotoutage during a period of operation of the safety pilot will permitcontinued operation thereof, with possible constant pilot relighttherefrom.

The invention contemplates that the pilot burners and their automaticvalves may be located in the combustion chamber of the main burner andtherefore subject to high ambient temperatures, as during main burneroperation, much beyond ambient temperatures during intervening periods;and a further object ofthe invention is to insure consistent operationof the apparatus, independent of its ambient temperatures.

The invention embraces the provision and employment of novel thermallyresponsive means, of dual character and arrangement such that the mainburner safety valve has operation solely responsive to the safety pilotburner and independent of ambient temperature, whereas the safety andconstant pilot valves may have operation not only responsive to theconstant pilot burner but also affected to some degree both by ambienttemperature and by the safety pilot burner. To these ends the dualthermally responsive device includes novel primary and secondary units,and relation therebetween, as will hereinafter appear.

Still another object is to combine in a compact relationship in a ruggedunitary device, the two pilot burners, the three automatic Valves, andthe dual thermally responsive means effective to actuate the valvesdependent upon pilot burner operation; all in arrangement whereinrelatively delicate parts have protection, yet necessary adjustmentthereof is provided and maintained.

Still another object is to provide an arrangement, wherein the twoburners and the three valves include parts which are portions of acommon base structure, upon which the dual thermally responsive deviceis mounted for control of the valves by the burners.

Further objects and advantages will be apparent from Ythe followingdescription taken in connection with the Iii) Patented Jian. 13, 1959accompanying drawings, which disclose an exempliiication of theinvention particularly adapted for employment within the oven of acooking range.

In the drawings,

Figs. 1 and 2 are views of a pilot burner assembly which includesautomatic main, safety pilot, and constant pilot gas supply valves; Fig.1 being generally in plan but showing the safety valve cover removed.,and the pilot burner valves in longitudinal section, as indicated by theline 1 1 of Fig. 2, and Fig. 2 being in elevation but partly broken awayto show details of construction;

Fig. 3 is a detail in sectional elevation of pilot burner partsappearing in Fig. 1, as indicated at line 3, Fig. l;

Fig. 4 is a view in sectional elevation generally as in the plane ofline 4 4 cf Fig. 1;

Fig. 5 is a view in isometric perspective of the dual thermallyresponsive device employed, together with main burner safety valve partsactuated thereby, the valve housing being indicated in broken lines;

Fig. 6 is a conventionalized diagrammatic view indicatin7 the principalparts, the circuit arrangement in which they are employed, and theirrelationship therein, the combustion chamber in which certain of theparts are located being indicated by a broken line; and

Figs. 7 to ll inclusive illustrate details of the dual thermallyresponsive device, Fig. 7 as a plan, Fig. 8 as in transverse section, asindicated by line 8-8 of Fig. 7, Fig. 9 in side elevation, Fig. 10 inend elevation, and Fig. ll as viewed from the bottom.

With reference now to the drawings, and rst to Figs. l to 4 thereof, abase structure is provided comprising principally a base castinggenerally indicated at A, which may be of cast iron, and shield means 3,firmly secured thereto oy rivets 3a, and which may be of heavy gaugestainless sheet steel.

The base A, together with `the shield means 3, constitute a common rigidbase structure for other parts of the unitary control device, as willappear hereinafter.

The safety valve may be of ball type including the ball 5 which seats ina horizontally disposed circular opening in its valve body l, whichlatter constitutes a portion of the base casting A.

The safety pilot means 2 includes a passage in the base A, as shown inFigs. l and 4, and a tip 6 ported as indicated at 7, Figs. l, 2 and 3.

The portion 7 includes an end portion to be in igniting relation to `themain burner to be served by the device, and side portions to be inigniting relation to a constant pilot burner and energizing relation toa thermally responsive device, all such portions being arranged forcoincident operation as known in the art.

rl`he shield means 3 is generally of elongated form, U- shaped intransverse section, extends along and laterally beyond the base A toprovide a hollow as indicated best in Fig. 4.

The dual thermally responsive device, generally indicated at d, isdisposed along and within the hollow provided by the shield Si. It is ofelongated form, and is mounted on the base A by the shield 3, with anend secured as by rivets i3 to the web of `the shield adjacent the pilotburner 2, and a free end adjacent the safety valve.

Actuating connection is provided effective between the free end of vthedevice and the bali 5 of the valve such that on operation of the safetypilot burner 2, to energize the device 4a', the ball S will be unseatedto open the main burner safety valve l, and upon safety pilot outage thevalve will close by gravity.

Arrangement for such actuation of the valve is illustrated in Fig. 5 asWell as indicated in Fig. l, and includes the rock shaft 8 mounted inthe valve body, a pin 9 mounted on the free end of the thermally responassente a sive device, a forked lever it@ on the rock shaft d outsidethe valve body and engaging the pin 9, and an arm lll within the valvebody to engage the ball 5.

What has thus far been described is known in the art, as exemplified in:

Patent No. 2,487,963, issued November 15, i949 to Cerny et al., forSafety Control for Oven Pilots and Main Burners.

Patent No. 2,487,969, issued November l5, i949 to Higley, for Eall ValveSafety Pilot Burners, and

PatentNo. 2,520,399, 'issued August 29, i956 to -iiglcy, for PilotBurner and Thermally Controlled Valve Therefor.

it should be 'noted vthat the above set forth operation of the Vsafetyvalve dependent upon operation of safety vipilot is had substantiallyindependent of `ambient temperature to which the assembly is subject, as

v. L. i The primary unit 4a 1s U-shaped in transverse section at itsbase end ll2, as indicated Figs. to 10, is provided with a slot 14 alongthe web of its U for a substantial distance adjacent :the base end, andis U-shaped for a substantial distance beyond the slot toward its freeend. Thus, along its slot 14 the unit includes a pair of legs in facingspaced relation, separated from each other by the lslot 14 butintegrally related with each other by the webs of the U therebeyond.

In the assembly, Figs. 1 and 2, the porting 7 of the safety pilot burner2 is such that its operation `will heat the near leg l5 of the primaryunit da. rfhe heat energy thus applied to one of the legs i5 will causethis leg to elongate relative to the other leg, which is relativelycooler, and being integral of the same coefficient of expansion.Therefore, the primary unit this energized, will effectively convert theinput of heat energy to one leg into mechanical energy, and flex tocause its free end to move vand open the safety valve. Upon pilot outageboth legs will be subject to the same ambient temperavture regardless ofits amount, the primary unit thus deenergized will strengthen, and thevalve will close.

The primary unit 4a may be recognized as generally of the type disclosedin Patent No. 2,455,306, issued November 30, 1948 to Frank R. Higley,for Thermally Responsive Unit.

The secondary unit 4b also includes a pair of leg members arranged inslightly spaced relation to provide a slotted eifect as at 16, Figs. 5and 7. One of its leg members is integral with that leg member le of theprimary unit 4a which is exposed to the safety pilot burner, and joinssuch primary unit leg member intermediate the ends Vof theislot i4. ithas an odset portion for a substantial distance along its length for itsdescribed slotted effect. The other leg of the secondary unit 4b is llatand secured to the first-named leg beyond the ends of the offset portionof the latter, as by welding. The straight leg of the secondary unit mayif desired be of a metal having a slightly lower coefficient ofexpansion than of the other three legs of the dual thermally responsivedevice, so that the free end of the secondary unit 4b will have a slightincrement of movement responsive to rise in ambient temperature, in thesame direction that the primary unit 4a is caused to move by heat fromthe safety pilot burner.

it will be apparent also that heat applied to the odset leg of thesecondary unit 4b will energize it to impart an increment of movement inthat direction, because of differential in temperature between the twolegs as described in connection with the primary unit 4a.

Moreover, since the efective base of the secondary unit 4b is upon a legi5 of the primary unit 4a, some of the movement of the primary unit 4awill be imparted as a third increment to the secondary unit 4b.

Thus, the free end of the secondary unit 4b may have differentiallyrelated and possibly cumulative increments of movement responsive toheat input, 'either (l) To both of its own legs due to rise in ambienttemperature,

(2) To its ofset leg only, as from the constant pilot burner, and/or (3)To thenear leg of the primary unit 4a, from the safety pilot burner.

Further according to this invention, the secondary` unit 4b of the dualthermally -responsive device, is employed for coincident automaticcontrol of a pair of twin valves.

With reference now particularly to Figs. l to 4 of the drawings, thesetwin valves include a safety pilot valve i8 and a constant pilot valve19 having a cciir-nrnonI valve body 2t?, which as illustrated may beintegral with the main base casting as a portion thereof.

Each of these twin valves is of the socalled normally open type, thatis, either will permit gas How indicated by the arrows in Fig. l, unlessclosed by depression of a plunger 22.

Furtherfdeta'ils of construction of these valves arenot ieri-al there,but Vas indicated in the drawings, they employ metal diaphragms wellknown in the art, vand lare 'of slight capacity.

rfhe plungers 22 of the twin valves have 'recessed 'heads as indicatedFig. l, and are interconnected as by an o'perating yoke y23, which haslingers arranged to seat in the head recesses, a stemportion extendingdownwardly and through a suitable opening in the shield 3 pastthe freeend of the secondary thermally 'responsive unit 4b, and therebelow hasloose forked `bearing on 'the 'end of :an adjusting 'screw 24, which is`mountedin the valve body Ztl. The yoke stem portion, serves as a lever,fulcrurned `on the screw 24, actuable by vthe secondary unit 4b, withmultiplying eiect on 'the twin 'vali/c5318 and i9, and is adjusted b'ythe screw 24 to provide that these valves will open upon slightenergization of Athe secondary 'unit 4b from any of the three sourcespreviously enumerated, and will otherwise be maintained closed by thesecondary unit, Ysuch valve operation being fast and automatic.

The safety pilot valve il@ has an outlet connection 25 to the i 't ofthe safety pilot burner 2 which may be drilled in he main base casting,as indicated in lbroken lines F g. l.

rEhe constant pilot valve it@ has a drilled outlet forming the baseportion of a constantzpilot burner 26, which latter may include a smalltube set into the valve body portion of the base A and`leadingtherefrcnn to a location within the shield 3, adjacent theporting 7 of the safety pilot burner to be in igniting relation with thelatter, and also in heating relation to the near hot or offset. leg ofthe secondary thermally responsive unit 4b.

The shield 3 is provided with a suitable top opening for ignition accessto the constantrpilot burncro and r i l of products of combustion fromthe constant and s.

e arcty pilot burners. l To protect the constant pilot burner fn againstoutage, the shield 3 may 'be perforate therebelow as at 2S. v

With reference now particularly to rzEig. 6 of the drawings, theapparatus described is arranged in the following manner to be eifectivebetween a 'fuel source X such as a gas manifold, and a main burner B forcontrol of the latter.

The safety valve l is arranged in a main gas line asesora U which leadsto the main burner B from the source X, by way of a main valve 31 aheadof the safety valve. The main valve 31 may be a manual valve asindicated or might be timer or thermostat controlled, as well known inthe art. A safety pilot gas line 32 leads to the safety pilot valve 1Ssubject to the main valve 31, as from the line St) ahead of the mainburner safety valve 1. A line 33 leads from the source X to the constantpilot valve 19, and may include a needle device 34 providing neadjustment of constant pilot gas to a very small amount.

Operation will be as follows, commencing with the apparatus shut down orcold, all the described valves being closed:

To light the constant pilot 2.6 a match may be applied to the exposedleg of the secondary thermally responsive unit 4b, which will cause thisunit to open the valve 19 and admit gas to the constant pilot burner,which gas will Ibe ignited 'by the match. Or the operator might manuallyopen the valve 19 yby manipulation of the yoke 23, ignite the constantpilot burner and allow the latter to heat the secondary unit 4b tomaintain the valve 19 in open position before releasing the yoke 23.

As the constant pilot valve 19 opens, so also does the safety pilotvalve i8, but no gas flows to the safety pilot burner 2 because the mainvalve 31 is closed.

When thereafter it is desired to operate the main burner B, the valve 31is opened. This admits gas to the main burner line 30 ahead of thesafety valve 1 but, since this valve-is closed, no gas yet reaches themain burner.

However, the safety pilot valve 18 beingopen, gas Hows to the safetypilot burner 2 by Way of the lines 32 and 25. The safety pilot burnerhas immediate ignition from the constant pilot burner 26. Operation ofthe safety pilot burner 2 energizes the primary unit 4a and causesopening of the safety valve .1 to admit gas to the main burner B, whichgas has immediate ignition from the safety pilot 2.

Energization of the primary unit 4a lby the safety pilot burner movesthe secondary unit 4b slightly farther from the yoke 23.

Assuming the automatic control parts to be located within the combustionchamber of the main burner B, as within a baking oven indicated by thebroken line BB in Fig. 6, ambient temperature to which the automaticcontrol parts are subject will rise. This may cause still furthermovement of the secondary unit 4b from the yoke 23 because of itsbi-metal construction.

Should ignition of the safety pilot burner 2 extinguish the minute flameof the constant pilot 26, reignition at the constant pilot burner mayresult from the continued operation of the safety pilot burner, which isof substantially greater relative capacity.

While the safety pilot 'burner 2 is operating and energizing its primarythermally responsive unit 4a, its effectiveness through the secondarythermally responsive unit 4b maintains the valves 18 and 19 openregardless of outage at the constant pilot 'burner 26.

Should such reignition of the constant pilot burner not so occur,nevertheless the main burner B will remain in operation so long as thesafety pilot burner 2 does, both however being subject at all times tothe main valve 31.

Should the safety pilot burner 2 cease operation from `any cause, itsoutage will deenergize its thermally responsive unit 4a and close thesafety valve 1 to discontinue operation of the main burner B, eventhough the main valve 31 remain open. Safety effect of the safety pilotburner 2, upon the main burner B, through the safety valve 1, is alwayspresent, because the primary unit 4a is independent of ambienttemperature.

After extinguishment of the safety pilot burner 2 for any reason, theconstant pilot burner 26 normally re- 4mains in `operation so thatdemand for operation of the main burner B may be satisfied by recyclingupon reopening of the main valve 31.

However, should the constant pilot burner 26 have become extinguished,the secondary thermally responsive unit 4b will eventually close bothvalves 18 and 19, andthe latter will remain closed until reestablishmentof the constant pilot burner. If the secondary unit 4b is of bi-metalconstruction as described, and should the ambient temperature of theautomatic control parts be high at the time of extinguishment of theconstant pilot burner, more than will be required to close the valves 18and 19, nevertheless they Will eventually be closed and the entireapparatus consequently automatically shut down.

During such period of high ambient temperature, coincident with constantpilot outage before the valve 18 closes, manual reignitiou of theconstant pilot burner is facilitated because its source of gas iscontinued, if the secondary unit 4b is somewhat responsive to ambienttemperature as described.

High ambient temperature from continued operation of the main burnernecessarily tends somewhat to distort relationships among the`relatively delicate automatic control parts. The described provision ofsome ambient temperature effect upon the secondary unit: 4b may serve ascompensation to prevent malfunctioning shut down under such conditions.

However, it will be appreciated that by employment of the same metal inboth legs of the secondary unit 4b, an advantage will be had in earliershut. down of the valves, on outage of the pilot 26 at high ambienttemperatures.

It is to be noted that in operation of the unitary control device shownin Figs. l to 4, all three of its valves and also the safety pilotburner, functionally are essentially under automatic control of theconstant pilot burner. The operation of the pilot burner is essentiallya prerequisite to the subsequent normal automatic operation of the otherelements of the device, which are interrelated With it as described.

Structurally, the interrelation of the two pilot burners and threeautomatic valves is had and positively maintained by three common rigidbase structures of the single base casting A plus the shield 3 rigidlyassociated therewith.

Also, it will be apparent that the unitary control device may beconveniently installed or removed for replace ment as a single elementof the control system in which it serves.

I claim:

1. In means for controlling operation of a main gas burner from a fuelsource therefor, and including a main valve, a safety valve, `and a maingas line leading from said fuel source to said main gas burner by way ofsaid main and safety valves successively, a safety pilot burner arrangedin igniting relation to said main burner, means thermally-responsive tosaid safety pilot burner for actuating said safety valve, wherebyoperation of said main gas burner is subject to operation of said pilotburner, a pilot gas line for said safety pilot burner arranged to besubject to said main valve, a constant pilot burner arranged in ignitingrelation to said safety pilot burner, a gas line for said constant pilotburner independent of said main valve, a pilot valve in said safetypilot gas line, a pilot valve in said constant pilot gas line, and meansthermally responsive to said constant pilot burne arranged to causeclosing of both said pilot valves, upon outage of said constant pilotburner and said safety pilot burner.

2. In means for controlling operation of a main gas burner from a fuelsource therefor, and including a main valve, a safety valve, and a maingas line leading from said fuel source to said main gas burner by way ofsaid main and safety valves successively, a safety pilot burner arrangedin igniting relation to said main burner, means assess/e I i' thermallyresponsive to said safety pilot burner for actuating said safety valve,whereby operation of said main gas burner is subject to operation ofsaid pilot burner, a pilot gas line for said safety pilot burnerarranged to be subject 'to said main valve, a constant pilot burnerarranged in igniting relation to said safety pilot burner,

a gas line for said constant pilot burner independent of said mainvalve, a pilot valve in said safety pilot gas line, a pilot valve insaid constant pilot gas line, and means thermally responsive to saidconstant pilot burner arranged to cause closing o-f both said pilotvalves, upon outage of said constant pilot burner and said safety pilotburner, said means thermally responsive to said constant pilot burnerbeing arranged to have movement away from said pilot valves whenenergized by operation of said constant pilot burner.

3. In means for controlling operation of a main gas burner from a fuelsource therefor, and including a main valve, a safety valve, and a maingas line leading from said fuel source to said main gas burner by way ofsaid Ymain and safety valves successively, a safety pilot burnerarranged in igniting relation to said main burner, means thermallyresponsive to said safety pilot burner for actuating said safety valve,whereby operation of said main gas burner is subject to operation ofsaid pilot burner, a pilot gas line for said safety pilot burnerarranged to be subject to said main valve, a constant pilot burnerarranged in igniting relation to said safety pilot burner, a gas linefor said constant pilot burner independent of said main valve, a pilotvalve in said safety pilot gas line, a pilot valve in said constantpilot gas line, and means thermally responsive to said constant pilotburner arranged to cause closing of both said pilot valves, upon outageof said constant pilot burner kand said safety pilot burner, said meansthermally responsive to said constant pilot burner being arranged tohave lost motion relative to said pilot valves when said means thermallyresponsive to said safety pilot burner is energized by operation of saidsafety pilot burner.

4. In means for controlling operation of a main gas burner from a fuelsource therefor, and including a main valve, a safety valve, and a maingas line leading from said fuel source to said main gas burner by way ofsaid main and safety valves successively, a safety pilot burner arrangedin igniting relation to said main burner, means thermally responsive tosaid safety pilot burner Vfor actu ating said safety valve, wherebyoperation of said main gas burner is subject to operation of said pilotburner, a pilot gas line for said safety pilot burner arranged to besubject to said main valve, a constant pilot burner arranged in ignitingrelation to said safety pilot burner, a gas line for said constant pilotburner independent of said main valve, a pilot valve in said safetypilot gas line, a pilot valve in said constant pilot gas line, and meansthermally responsive to said constant pilot burner arranged to causeclosing of both said pilot valves, upon outage of said constant pilotburner and said safety pilot burner, said means thermally responsive tosaid constant pilot vburner being arranged to have movement in pilotvalve opening direction responsive to its energization by operation ofsaid constant pilot burner, and to have further movement in saiddirection responsive to energization of said means thermally responsiveto said safety pilot burner by operation of said safety pilot burner.

5. in means for controlling operation of a main gas burner from a fuelsource therefor, and including a main valve, a safety valve, and a maingas line leading from said fuel source to said main gas burner by way ofsaid main and safety valves successively, a safety pilot burner arrangedin igniting relation to said main burner, means thermally responsive tosaid safety pilot burner for actuating said safety valve, wherebyoperation or". said main gas burner is subject to operation of saidpilot burner, a pilot gas line for said safety pilot burner arranged tobe subject to said main valve, a constant pilot burner Cil arranged inigniting relation to said safety pilot burner, a gas line for saidconstant pilot burner independent of said main valve, a pilot valve insaid safety pilot gas line, a .pilot valve in said constant pilot gasline, and means thermally responsive to said constant pilot burnerarranged for movement in one direction to cause closing of both saidpilot valves, upon outage of said constant pilot burner and vsaid safetypilot burner, said means thermally responsive to said constant pilotburner being arranged to have movement in the opposite directiondependent upon its energization by operation of said constant pilotburner and also dependent upon rise in its own ambient temperature.

6. In means for controlling operation of a main gas burner from a fuelsource therefor, and including a main valve, a safety valve, and a maingas line leading from said fuel source Hto said main gas burner by wayof said main and safety valves successively, a safety pilot burnerarranged in igniting relation to said main burner, means thermallyresponsive to said safety pilot burner for actuating said safety valve,whereby operation of said main gas burner is subject to operation ofsaid pilot burner, a pilot gas line for said safety pilot burnerarranged to be subject to said main valve, a constant pilot burnerarranged in igniting relation to said safety pilot burner, a gas linefor said constant pilot burner independent of said main valve, a pilotvalve in said safety pilot gas line, a pilot valve in said constantpilot gas line, and means thermally responsive to said constant pilotburner arranged to have movement in one direction to cause closing ofboth said pilot valves, upon outage of said constant pilot burner andsaid safety pilot burner, and to have movement in the opposite directiondependent incrementally upon its energization by operation of saidconstant pilot burner, upon the energization of said means thermallyresponsive to said safety pilot burner by operation of said safety pilotburner, and upon increase in its own ambient temperature.

7. A dual thermally responsive device of the class described comprisinga pair of thermally responsive units, each of elongated form adapted forlateral deflection to produce movement of a relatively free end whenmounted at its opposite extremity as a base end, one of said unitsconstituting a primary unit and being of a type responsive totemperature differential between portions intermediate its ends andunresponsive to ambient temperature, the other of said unitsconstituting a secondary unit, and being of a type responsive to ambienttemperature, the base end of said 'secondary unit being secured to saidprimary unit-at a location removed from the base end of the latter,whereby the free end of said secondary unit will have movementdifferentially responsive to ambient temperature and to said primaryunit.

8. A dual thermally responsive device Vof the class described comprisinga pair of thermally responsive units, each unit having `a pair ofelongated members generally of strip form disposed alongside each otherin facing relation, the members of said 'pair having portionsintermediate their ends arranged in spaced relation to each other andinterconnected portions endwise therebeyond, one of said unitsconstituting a primary unit, its said members being of the same materialand their said endwise portions being integrally interconnected, wherebyone end portion of said primary unit may be mounted to serve as a baseend, and 'the other end portion serve as a movable Vend responsive totemperature differential between the intermediate portionsof its membersand independent of ambient temperature, the other of said unitsconstituting'a secondary unit, its said members being of materials `of'dilerent coeicients of eX- pansion, one of said endwise portions ofSaid secondary unit being mounted on one of said `members of saidprimary unit at said intermediate portion thereof, Whereby to serve as abase end for said secondary unit, with the other end portion as amovable end, whereby said movable end of said secondary unit will havemovement differentially responsive both to ambient temperature and totemperature differential between the intermediate portions of itsmembers, and also to movement of said primary unit.

9. A dual thermally responsive device of the class de` scribedcomprising a pair of thermally responsive units, each unit having a pairof elongated members generally of strip form disposed alongside eachother in facing relation, the members of said pair having portionsintermediate their ends arranged in spaced relation to each other andinterconnected portions endwise therebeyond, one of said unitsconstituting a primary unit, its said members being of the same materialand their said endwise portions being integrally interconnected, wherebyone end portion of said primary unit may be mounted to serve as a baseend and the other end portion serve as a movable end responsive totemperature differential between the intermediate portions of itsmembers and independent of ambient temperature, the other of said unitsconstituting a secondary unit, one of its said members being integralwith said primary unit, and the other of a material of differentcoefficient of expansion, an endwise portion of the integral member ofsaid secondary unit being joined to one of said members of said primaryunit at said intermediate portion thereof whereby to serve as a base endfor said secondary unit, with the other end portion as a movable end,whereby said mov-` able end of said secondary unit will have movementdifferentially responsive both to ambient temperature, and totemperature differential between the intermediate portions of itsmembers, and also to movement of said primary unit.

10. In means for controlling operation of a main gas burner from a fuelsource therefor, and including a main valve, a safety valve, and a maingas line leading from said fuel source to said main gas burner by way ofsaid main and safety valves successively, a safety pilot burner arrangedin igniting relation to said main burner, means thermally responsive tosaid safety pilot burner for actuating said safety valve, wherebyoperation of said main gas burner is subject to operation of said pilotburner, a pilot gas line for said safety pilot burner arranged to besubject to said main valve, a constant pilot burner arranged in ignitingrelation to said safety pilot burner, a gas line for said constant pilotburner independent of said main valve, a pilot valve in said safetypilot gas line, a pilot valve in said constant pilot gas line, and meansthermally responsive to said constant pilot burner arranged to causeclosing of both said pilot valves, upon outage of said constant pilotburner and said safety pilot burner, enclosure means arranged about saidmain, safety pilot and constant pilot burners, their said. safety,safety pilot and constant pilot valves respectively, and said thermallyresponsive means, to provide a combustion chamber for said burnerswithin which ambient temperature is affected by `burner operation, saidmeans thermally responsive to said constant pilot burner being arrangedto have movement in the direction for opening of said pilot valvesdependent upon its energization by operation of said constant pilotburner and also dependent upon increase in said ambient temperature.

11. A unitary control device for the purpose described comprising mainburner safety valve means, safety pilot burner means, safety pilot valvemeans arranged for control of said safety pilot burner means, constantpilot `burner means for ignition of said safety pilot burner means, andconstant pilot valve means arranged for control of said constant pilotburner means, all of said means including parts which are portions of acommon base structure, and thermally responsive means mounted on saidbase structure and arranged for control of said main burner safety valvemeans by said safety pilot burner means, and also arranged for controlof both of said safety pilot valve means and said constant pilot valvemeans by said constant pilot burner means.

12. A unitary control device for the purpose described comprising mainburner safety valve means, safety pilot burner means, safety pilot valvemeans arranged for control of said safety pilot burner means, constant,pilot burner means for ignition of said safety pilot burner means, andconstant pilot valve means arranged for control of said constant pilotburner means, all of said means including parts which are integrallyrelated portions of a common base structure, and thermally responsivemeans mounted on said base structure and arranged for control of saidmain burner safety valve means by said safety pilot burner means, andalso arranged for control of both of said safety pilot valve means andsaid constant pilot valve means by said constant pilot burner means.

References Cited in the le of this patent UNITED STATES PATENTS

